Waste management is a major challenge for may animal feeding operations agricultural production and processing operations, and food service businesses. Nearly 40% of feed dry matter and up to 70% of nutrients fed to the animals is excreted in manure, and increasingly significant amounts of labor and capital are being invested in efforts to better manage this organic material. Plant residues and processing byproducts need to be more efficiently managed and utilized as valuable resources.
Liquid manure handling and storage systems are commonly used on livestock farms. Most of the water used on livestock farms and later added into the manure system originates from building and equipment washing activities. In the areas where water resources are limited and/or disposal of a large quantity of wastewater is problematic, reclamation of clean water from animal wastewater is necessary. Producing biogas for fuel and nutrient-rich fertilizer products while simultaneously achieving water reclamation will help with the economics of wastewater treatment. Thus there is a need for an energy efficient, integrated animal wastewater treatment system for water reclamation as well as biogas and organic fertilizer production. The present invention solves this and other wastewater treatment problems
Due to high concentrations of organic and inorganic matter present in wastewater, extensive pretreatment is normally required to assure normal operation of reverse osmosis (RO) membranes. Due to high treatment cost, reclamation of clean water from animal wastewater normally is not an economically favorable endeavor, unless other valuable products can be produced along with water to offset the cost of wastewater treatment. Combining biological treatment processes, such as anaerobic digestion, with membrane separation have been attempted before by Bilstad et al. (Bilstad et al., Wat. Sci. Tech. 25(10):19–26 (1992)). Reverse osmosis (RO) coupled with anaerobic digestion as pretreatment was studied in both pilot and full scale. An RO module consisted of 18 tubular polyamide membranes were used to treat the anaerobically digested pig manure that had undergone chemical treatment and mechanical solid-liquid separation. The pilot membrane separation trials were performed on a batch basis, i.e. the RO reject was returned to the feed tank. After RO treatment, 95% of total nitrogen was removed from the liquid fraction. The efficacy of using an integrated anaerobic and aerobic treatment system for animal wastewater has been demonstrated. (Li and Zhang, American Society of Agricultural Engineers Meeting, Sacramento, Calif. ASAE Paper No. 012294 (2001)).
Water reclamation from wastewater requires removal of organic and inorganic compounds from water. Membrane separation technologies have been applied to separation of solids and recovery of materials from waste streams, purification of polluted water, and desalination of salt water. (Duvel and Helfgott, J of Water Pollution Control Fed. 47:57–65 (1975); Bilstad, Science 102:93–102 (1995); and Ozaki and Li, Water Research 36:123–130 (2002)). Practical membrane applications vary from small-scale batch to large, continuous separations. Reverse Osmosis (RO) is one of the commonly used membrane separation processes. It is capable of removing a wide spectrum of impurities in liquids at high efficiencies. (Bilstad, 1995, supra). For applications of domestic and industrial applications, solids sedimentation and chemical precipitation are common pretreatment methods prior to membrane separation (Lopez-Ramirez et al., Water Research 37:1177–1184 (2002)).
There is a need for an integrated system of waste treatment to provide highly purified end products that do not require further treatment. The present invention solves this and other problems.